CZ347898A3 - Water-containing solid cleansing agent and process for producing thereof - Google Patents

Abstract

This invention concerns preparation of compact cleaning agent for industrial dish washing machines with high alkaline cleaning substances based on alkali hydroxide, and preferably sodium hydroxide which combine the advantages of powders and liquids on the one hand and of tablets and melt blocks on the other. Moreover, the solidity of the cleaning substances can be varied in a controlled manner during production and storage. This is possible by mixing an aqueous alkali solution with a compound of formula (I) HOCH<2>CH(R<1>) and/or of formula (II) [HOCH<2>XH(R<8>)3-xNHx, to increase the viscosity and then adding solid alkali hydroxide, preferably potassium or sodium hydroxide, most preferably sodium hydroxide.

Description

Water containing a solid detergent and a process for its manufacture

Technical field

The invention relates to a solid dishwashing detergent composition. To achieve consistent consistency, the detergent composition comprises glycols and derivatives thereof and / or alkanolamines and alkali metal hydroxides in solid form.

BACKGROUND OF THE INVENTION

Alkali-containing cleaning compositions are currently commercially available, for example, as powders, granules, liquids, blocks or tablets made by compression.

Each of these forms has specific advantages and disadvantages for the intended use. Powders, granulates or liquids are used for cleaning surfaces of textile materials or for manual mechanical cleaning of hard surfaces, while for mechanical cleaning of hard surfaces, for example for washing dishwashers, in addition to powders, granules or liquids, tablets, prepared by compression or blocks are increasingly used. formed by melting followed by cooling. Tablets and blocks have the advantage of simple dosing over powdered materials, they do not dust and are easy to handle.

These advantages can be utilized, for example, in the case of domestic dishwashers, but especially in the case of continuously operating large industrial dishwashers in which the dishes are conveyed through different washing areas.

It has now been found that very hard tablets and very hard blocks also have a disadvantage. For example, cracks may form on hard tablets and damaged tablets can no longer meet the exact dosage requirement. Another problem associated with 9 9 9 9 9 9

- 2 using tablets is that it is not always possible to achieve the desired water solubility, so that the tablets dissolve too quickly or too slowly. In the case of blocks prepared by melting and cooling, high rigidity for transport is required, but there are problems in dispensing these very solid detergents. In addition, the manufacture of block 1 tablets is expensive, since high demands are placed on the use of materials and the process conditions in the processing of alkaline melts.

High homogeneity of detergent compositions is also particularly desirable, but is difficult to achieve in the case of solid compositions. This problem hardly affects liquid formulations which are easy to mix. Also desired is the homogeneity of the liquid, viscous liquid, or miscible paste, which is then allowed to solidify in a controlled manner to formulations of varying strengths that take advantage of storage, transport and dosage benefits. In this case, it is desirable to maintain the miscibility of said blanks at temperatures up to 40 ° C, since components which are no longer stable at higher temperatures can then be added.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cleaning agent based on alkali metal hydroxides, in particular potassium or sodium hydroxide, and in particular sodium hydroxide, for use on textile surfaces, in particular for cleaning hard surfaces such as dishes and especially for dishwashing in industrial dishwashers. combine the advantages of powder and liquid formulations as well as the benefits of tablet or block formulations. This means that the formulation should have a defined solubility under all conditions, be stable during storage and transport, and allow rapid, simple and accurate dosing, at the same time being non-flat and costly to manufacture and refill Into the packaging • · ······························ ·· ··

- 3 should be simple. Particular consideration should be given to the stirrability of the materials during manufacture, the variability of the strength of the detergent during manufacture and storage, thereby achieving great advantages. It should be possible to carry out the process at a temperature below 42 ° C in order to avoid damage to possible less stable components.

It goes without saying that the usual requirements for cleaning agents such as good cleaning power, fat dissolution and the like must also be met.

Highly viscous to paste detergents have been described as well as solid detergents in the form of tablets or blocks.

For example, DOS 31 38 425 describes the rheological properties of the disclosed cleaning composition. It is a gel-like paste which can be liquefied by means of mechanical forces, for example by shaking or by pressure or by means of a metering pump, and easily pushed out of the metering nozzle.

U.S. Pat. No. 3,607,764 discloses a solid glass cleaner which can be diluted to a sprayable solution. The composition includes, but is not limited to, sodium or potassium hydroxide, sodium or potassium polyphosphate, sodium or potassium pyrophosphate hydroxycarboxylic acids, such as bullders, water-soluble nonionic surfactant, alkylene glycol ethers, and optionally sodium carbonate. The possibility of controlling the viscosity or mechanical strength of the composition is not disclosed.

Japanese Patent JA 84/182870 describes solutions of alkali metal hydroxides in glycols or alcohols which become neutral with long chain carboxylic acids by the addition of silicone oil

they have a pasty consistency and can then be used as a paste to lubricate leather.

Japanese Patent JA 86/296098 discloses anhydrous solid alkali metal hydroxide cleansers. These are mixed with alkanolamines and water-soluble glycol ethers to form a solid detergent. There is no mention of a variable reduction in the strength of the cleaning composition.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention is based on a water-containing solid detergent composition with controlled variable strength that provides a temperature of up to 25 mm, preferably 0.1 to 25 mm, at 20 ° C in a penetration test according to ISO 2137;

a) an aqueous alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, preferably 42 to 55% in an amount of 21 to 70, preferably 35 to% by weight and to increase the viscosity

(b) a compound of formula (I) hoch ₂ ch (r ¹ ) or ² (I) wherein R ¹ is hydrogen or methyl; and

R is independently hydrogen, C 1 -C 4 alkyl, CH CH (R ³ ) OR ^4, or CH CH (R ⁵ ) 0CH CH (R ⁶ ) OR ⁷ , wherein R, FC and R 0 are hydrogen or methyl

And R and R are hydrogen or alkyl of 1 to 4 carbon atoms, and / or compounds of formula II

HOCH 2 CH (R ⁸ ) 3 NH

3-x x (II) to • to to toto toto • toto toto <<<<<<<<<<<<<

Where R is a hydrogen atom or methyl and x is an integer of 0, 1 or 2, in a total amount of 0.5 to 40%, preferably 1 to 10% by weight based on the total weight of the detergent, then solid alkali hydroxide is added % metal in an amount of up to 35% by weight.

The ISO 2137 standard, which is also given in the example section, refers to the penetration measurement using calibrated metal cylinders, the penetration depth is measured. The test is feasible even if the metal cylinder with the smallest diameter can still penetrate the test substance. Without intending to limit the invention to particular embodiments, some embodiments in which strength can be varied will be listed.

The detergent compositions of the present invention cannot leak from a container, for example a glass container, facing downwards at a temperature of 20 to 40 ° C. Consistency of the composition can also be expressed by mechanical strength. Many of the detergent compositions of the present invention can still be processed into a different shape during processing and storage.

The invention also relates to a method for producing said composition and to its use for machine dishwashing.

In order to achieve the desired consistency, it is essential to select the right amount of individual components.

For example, it has been found that the solid compositions described in U.S. Pat

607 764 cannot be converted in a simple manner by successive dilution with water to a cleaning agent with controlled theological properties according to the invention.

• »

It has also been found that using a sodium hydroxide solution in an alcohol or glycol, it is not possible to obtain a homogeneous composition even after the addition of additional solid hydroxide.

On the other hand, it has unexpectedly been found that besides a thickener and, for example, a solid alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, no other components are required to achieve the desired consistency in aqueous sodium hydroxide. It should therefore be pointed out that the addition of compounds of formula I or II to an alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, is already sufficient to achieve controlled strength.

The water content, which is to be in the range of 10 to 35, preferably 20 to 30% by weight, is also a critical parameter.

Due to the high NaOH content, the pH of the detergent composition according to the invention is higher than 13.

However, the detergent compositions of the present invention can also be used in combination with other compositions without losing the variable strength of the composition. In such cases, the cleaning agent consisting of an alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, compound I and / or II and a solid alkali metal hydroxide, preferably sodium hydroxide, serves as a carrier phase for the other components common in such compositions .

The cleaning composition may additionally contain, for example, a builder-type material in an amount of up to 60, preferably 15 to 40% by weight.

The builder-type substance contained in the detergent composition according to the invention may, in principle, be any substance which is: ·· ·· · fr «· ti

- for this purpose, in the broadest sense, said to be suitable for washing and cleaning agents, preferably those which are water-soluble.

Examples of builder compounds include alkali metal phosphates, for example sodium or potassium. Particular preference is given to tetra-sodium diphosphate, pent-sodium triphosphate, sodium hexamethaphosphate and the corresponding potassium salts or a mixture of sodium hexamethaphosphate and the corresponding potassium salts or mixtures of sodium and potassium salts.

In addition, complexes of this type, such as nitrilotriacetate or ethylenediaminetetraacetate, may be mentioned. Sodium carbonate and borax also belong to substances of this type.

Other water-soluble builders are, for example, organic polymers, natural or synthetic, especially polycarboxylates. Examples are polyacrylic acids and copolymers of maleic and acrylic anhydrides as well as sodium salts of these polymeric acids. Among the commercially available products, such materials include, for example, Sokalan ^R CP 5 and PA 30 (BASF), Alcosperse (R) 175 and 177 (Alco), LMW (R) 45 N, and SP02 ND (Norsohaas). Natural polymers include, for example, oxidized starches, for example according to DE 42 28 786 and polyamino acids, such as polyglutamic acid or polyaspartic acid, which are supplied, for example, by Cygnus, Bayer, Rohm and Haas, Rhone-Poulenc or SRCHEM.

Other useful builders are naturally occurring hydroxycarboxylic acids, for example mono- or dihydroxysuccinic acid, alpha-hydroxypropionic acid, citric acid, gluconic acid and salts thereof. The citric acid salts are preferably sodium citrate dihydrate.

«A

Other builders include amorphous metasilicates or layered silicates. Examples of crystalline silicates are those which are sufficiently alkaline stable and are available, for example, from Hoechst AG, Germany under the trade name Na-SKS, for example Na-SKS-1 (Na ₂ Si ₂₂ 0 _45. XH ₂ 0, kenyaite), Na -SKS-2 (Na ₂ Si ₁₄ O _{2 g.} xlfyO, _{magadiite :)) The} _SKS-3 (Na ^ ^ iGO. xH ₂ O), Na-SKS-4 (Na ₂ Si ₄ O _g. xlfyO, makatite) Na-SKS-5 (/ U-Na ^ Si ^ Ch), Na-SKS-7 (beta-Na-Si-CL ·, natrosilit), Na-SKS-11/2 dbd ά ό (tau-Na ₂ Si ₂ O ₅ ), and Na-SKS-6 (delta-Na ₂ Si ₂ O _g ).

Particularly preferred builder-type substances are selected from the group consisting of pentane sodium triphosphate, sodium citrate, nitrilotriacetate, ethylenediaminetetraacetate, and mixtures thereof.

The compositions of the invention may also contain conventional bleaching agents. They may be oxygen-based agents such as perborate sodium, optionally in the form of hydrates or sodium percarbonate, or they may be chlorine-based bleaching agents such as chloro-p-toluenesulfonic acid amide, trichloroisocyanuric acid, alkali metal dichloroisocyanurate, hypochlorites alkali metal and hypochlorite releasing substances, with alkaline-stable bleaching agents being particularly preferred. They may be directly alkaline-stable compounds or processed, for example, by coating or passivation.

The compositions according to the invention may also contain weakly foaming surfactants, in particular nonionic surfactants in amounts of up to 10%, preferably up to 5% by weight. It is also possible to use very non-foaming substances. These may be, for example, alkylpolyethylene glycolpolypropylene glycol ethers having an alkyl moiety of 12 to 18 carbon atoms each containing 8 moles of ethylene oxide and propylene oxide units per molecule. However, other known non-foaming nonionic surfactants may also be used, for example.

alkylpolyethylene glycol polybutylene glycol ethers having from 12 to 18 carbon atoms in the alkyl moiety and about 8 moles of ethylene oxide and butylene oxide units per molecule, as well as mixed ethers of alkyl polyalkylene glycols. In particular, the detergent compositions of the present invention are fully effective even without such additives, which may, however, facilitate cleaning.

Other possible components of the compositions of the invention are suds suppressors. These substances can be used, for example, if the surfactant selected under the operating conditions foams too much so that no foam remains in the dishwasher.

Paraffin oil may also be used, although the composition of the invention is fully effective even without this component.

Optional ingredients may also be other conventional detergent ingredients, such as dyes or perfumes, stable in an alkaline environment.

The composition according to the invention may also contain abrasives, but preferably they do not.

In principle, thickeners, for example, swellable silicate clays of the montmorillonite, bentonite, kaolin, talc or carboxymethylcellulose type may be used to modify the strength and consistency, but these materials are not essential and may be omitted completely.

An essential feature of the composition according to the invention is the exploitation of the combined effect of the compounds of the formulas I and II together with a solid alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide.

Thus, it is the use of the compounds of the formula I and / or

II in combination with solid NaOH for the reinforcement of water-containing cleaning compositions for machine dishwashing containing alkali metal hydroxide, preferably sodium hydroxide.

A further object of the invention is also a process for concentrating an aqueous solution of an alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide at a concentration of 42 to 55% by weight. In this process, a compound of formula I and / or II is added to the NaOH solution with stirring to form a paste-like mixture to which a solid is selected from the group of builders and an alkali metal hydroxide, preferably potassium or sodium hydroxide, especially potassium hydroxide or mixtures thereof, the process is carried out at a temperature of 20 to 50, preferably 30 to 48, and especially 38 to 42 ° C.

At higher temperatures, the solubility of NaOH in water increases and the NaOH content of the aqueous solution may be higher than 55% by weight. On the other hand, at lower temperatures, the NaOH content may also be less than 42% by weight. Thus, limiting the NaOH content to 42-55% by weight is substantially limited to the stated temperature range of 20-25 ° C.

An important advantage of the invention is that the stirrability and the associated advantages are already ensured at room temperature. In many cases, for example at a very high viscosity of an alkali metal hydroxide solution after concentration, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, it may be appropriate to raise the temperature somewhat before the addition of solid additives. However, the consistency of the invention can be achieved in almost all cases at a temperature below 42 ° C, preferably a temperature range of 38 to 42 ° C, so that components with lower temperature stability, such as chlorine bleaching agents, can also be processed.

In a preferred embodiment of the process according to the invention, the mixture is stirred for at least 3 minutes before addition of solid sodium hydroxide after the addition of the compounds of the formulas I and / or II.

«··· * · ···· ··

If the thickened composition is to contain builders, these may also be added beforehand to the alkali metal hydroxide solution to be thickened, preferably potassium or sodium hydroxide, and in particular sodium hydroxide. Preferably, however, the builders are added to the already thickened pasty mixture at a higher temperature such that the builder mixture is already formed of an alkali metal hydroxide solution, preferably potassium or sodium and especially sodium, a compound of formula I and / or II and solid sodium hydroxide. Also, further optional components are preferably added at a higher temperature to the already thickened paste mixture of an alkali metal hydroxide solution, preferably potassium or sodium and especially sodium, a compound of the formula I and / or II and solid sodium hydroxide.

The cleaning agent according to the invention can be used, for example, by spraying the cleaning agent in a package of, for example, 0.5 to 10 kg with a controlled strength, with water and, for example, adding the dissolved cleaning agent to the dishwasher.

For example, a Topmater P40 dosing device (Henkel Hygiene GmbH) or a V / VT-2000 dosing device (Henkel Ecolab) may be used for this purpose.

The cleaning composition according to the invention can be prepared in a mixing device at a temperature of 20 to 50, preferably 30 to 48 and in particular 38 to 42 ° C. The detergent is then filled at about 40 ° C into a package to be transported and cooled in a cooling tunnel to about 20 ° C to achieve the desired consistency.

However, another procedure may be used to fill and cool to room temperature.

fc * «·

- 12 fcfcfc

The detergent compositions of the present invention have somewhat increased their hardness, which has been verified by measurement over time. This procedure is highly dependent on the composition of the composition. Thus, it may be possible that some formulations cannot penetrate any of the rollers after a few weeks of penetrometric testing according to ISO 2137. Thus, the breakthrough data refers to a period of hours to days after manufacture of the composition of the invention.

The following examples are intended to illustrate the invention.

DETAILED DESCRIPTION OF THE INVENTION

Detergents of kg weighing 1 to 8 were prepared in each case. A 50% alkali metal hydroxide solution in water was placed in a 1 liter beaker as a template. While stirring with a mechanical stirrer at 100 rpm, 1,2-propylene glycol was added at 40 ° C and after the addition was complete the mixture was stirred for a further 5 minutes and then solid sodium hydroxide was added as the alkali metal hydroxide. Optionally, additional solids (builders) were added with stirring and after the addition was completed the mixture was stirred again for 5 minutes. The penetration tests according to ISO 2137 were carried out in a standard manner at room temperature of 22 ° C at 5, 24 and 48 hours after manufacture of the detergent. The values given are averages of three measurements. Since insoluble components with different particle sizes may be present in the pasty detergent, the measured values may be dispersed approximately ± 20%.

The amounts in the following table refer to mixtures in grams to facilitate comparability of the effects of the various components during the different process steps.

• · · · · · · · · · · ·

99,999 • 9

9 9 9

B1 B2 B3 B4 B5 B6 B7 B8 sodium hydroxide hydroxide Potassium ~ MeOH (50% aq) 57.5 53 53 53 53 39.5 39.5 39.5 1.2 Propylenalycol 6 5.5 5.5 5.5 5.5 4 - Parrafin S! K 1.5 1 ' 1.5 1.5 1.5 1.5 1.5 1.5 NaOH (solid) 10 15 Dec 15 Dec 15 Dec 30 30 30 Acetonitrile 92% 25 25 - 25 25 25 25 • penetration (mm) 5 hours 5.5 2.7 8.3 26.8 2.9 0 0 0 penetration (mm). 24 hours 4,5 2,0 7.0 19.7 2.4 0 0 0 penetration (mm) 48 hours 3.2 1,8 7.2 17.8 2.9 0 0 0

All mixtures are homogeneously miscible and refillable into containers. However, subsequent curing of the composition takes place in compositions of different compositions with different speeds.

The various components have different effects on the strength and the variability of this strength, as will be briefly explained below.

A comparison of Examples B1 and B2 shows the effect of the amount of solid alkali metal hydroxide on the changes in strength of the mixture.

Increasing the proportion of solid alkali metal hydroxide increases the strength, which means less penetration in the penetrometric test.

Example B3 shows the effect of adding an optimal builder compared to Example B2. The addition of this material leads to an increase in strength, but achieving this consistency is possible even without the addition of a builder.

In Example B4, the effect of adding solid alkali metal hydroxide is demonstrated in more detail compared to Example B2.

• · · · ·

• · »

By adding solid alkali metal hydroxide, the desired strength increase is again achieved.

In Example B5, the order of addition of nitrilotriacetic acid and solid sodium hydroxide was altered compared to Example B2. Even with this change, the desired properties of the composition of the invention are achieved.

In Examples B6, B7 and B8, an aqueous potassium hydroxide solution was used instead of an aqueous sodium hydroxide solution.

In the examples, the mixture is only miscible for a short time due to the high solids content of NaOH. The hardening proceeds so quickly that after 5 hours no penetration can be observed in the penetration test. However, the required properties are achieved when the test is carried out shortly after mixing the mixture.

For comparison, a number of cleaning compositions were prepared without the addition of compounds of Formula I or II, optionally without addition of solid NaOH. The results are summarized in the following table.

V1 V2 V3 V4 V5 V6 sodium hydroxide 20 May 25 30 35 90 80 Propytenalycoi - - - - 10 20 May Parrafin SiK - - - - - - carbonate sodium 30 20 May 20 May 10 - - NaOH (solid) - - - - - - ýoda 20 May 25 30 35 - - nitrilotriacetic acid 92% 30 30 20 May 20 May penetration (mm) according to ISO 2137 19.5 4

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

In Example VI, a homogeneous detergent is not obtained but a wet lumpy powder.

In the case of the compositions of Examples V2, V3 and V4, after storage for 1 day at 25 DEG C., the phases are separated, i.e. the aqueous phase is separated.

Examples V5 and V6 show particularly the considerable effect of the addition of solid alkali metal hydroxide, since only the addition of large amounts of gyphthol could achieve consistency according to the invention and the ability to vary the strength of the composition was severely limited.

Claims (17)

PATENT CLAIMS Water containing a fixed, variable strength controlled cleaning agent which provides at a temperature of 20 ° C in a penetration test according to ISO 2137 a value of up to 25 mm, preferably 0.1 to 25 mm, obtainable by a mixing process a) an aqueous alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, preferably 42 to 55% in an amount of 21 to 70, preferably 35 to 55, 55% by weight and to increase viscosity b) a compound of the general formula 1 hoch ₂ ch (r ¹ ) or ² (I) wherein R 6 represents a hydrogen atom, 2: or a methyl group, and R 6 is independently hydrogen, C 1 -C 4 alkyl, <CH 3 (R ³ ) OR 4, or CH CH (R ⁵ ) OCH CH (R 0) OR ⁷ , R 'where R groups and R> 2 ^ ⁱⁱ azomy hydrogen or methyl denote I 7 and R represent hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, and / or compounds of formula II hoch ₂ CH (R °) ₃ _ _x nh _x (II) wherein R represents a hydrogen atom or methyl and x represents an integer of 0, 1 or 2, in a total amount of 0.5 to α, preferably 1 to 10% by weight, based on the total weight of the detergent composition; 9 9 9 9 · 9 9 9 9 9 9 9 9 · · · 9 9 999 999 9 9 9 9 9 999 99 99 99 99 17, then solid alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, is added in an amount of up to 35, preferably 2 to 25% by weight. Water-containing solid detergent composition according to claim 1, characterized in that it further comprises a builder-type substance in an amount of up to 50, preferably 15 to 40% by weight, based on the total weight of the composition. 3. A water-containing solid detergent composition according to claim 2 wherein the builder is selected from the group consisting of pentane sodium triphosphate, sodium citrate, nitrilotriacetate, ethylenediaminetetraacetate, sodium carbonate, alkali metal metasilicate, and mixtures thereof. A water-containing solid detergent composition according to any one of claims 1 to 3 wherein the compound of formula I is selected from ethylene glycol, 1,2-propylene glycol, butyl glycol, butyldiglycol and the compound of formula II is selected from ethanolamine, diethanolamine and triaethanolamine. Water-containing solid detergent composition according to any one of claims 1 to 3, characterized in that 1,2-propylene glycol is used as the compound of formula I and diethanolamine as the compound of formula II. 6. A process for the production of a water-containing solid detergent containing alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide for dishwashing, characterized in that it is admixed. a) an aqueous alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, preferably 42 to 55% in an amount of 21 to 70, preferably 35 to 55, 55% by weight and to increase viscosity b) a compound of formula (I) hoch ₂ ch (r ¹ ) or ² (I) wherein R ³ represents a hydrogen atom or a methyl group and R independently represents a hydrogen atom, an alkyl of 1 to 4 carbon atoms, a CH CH (R ³ ) OR group wherein CH 2 CH (R ⁵ ) OCH 2 C (R ⁶ ) CR ⁷ wherein R, R and R are hydrogen or methyl and R ⁴ and R ⁷ are hydrogen or C 1 -C 4 alkyl, and / or compounds of the general formula ± 1 HOCH CH (R ³ ) NH (II) 2 <s-x x Where R is hydrogen or methyl and x is an integer of 0, 1 or 2, in a total amount of 0.5 to 40, preferably 1 to 10% by weight based on the total weight of the detergent composition, followed by solid alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide in an amount of up to 35, preferably 2 to 25% by weight. Method according to claim 6, characterized in that the alkali metal hydroxide used is sodium hydroxide in part in the form of a solution having a concentration of 42 to 55% by weight and in part as a solid. 99 9 9 9 9 9 9 9 9 ··· · · ·· · * · * A process for strengthening aqueous sodium hydroxide solutions having a concentration of 42 to 55% by weight, characterized in that a compound of formula I and / or II as defined in claim 1 and, in addition, an alkali hydroxide are added to said solution while stirring. metal, preferably potassium or sodium hydroxide, and especially sodium hydroxide in solid form. A method of solidifying an aqueous solution of sodium hydroxide at a concentration of 42 to 55% by weight, characterized in that a compound of formula I and / or II as defined in the main claim and from 0.1 to 35 is added to said solution while stirring. % sodium hydroxide in solid form. Process according to one of Claims 6 to 9, characterized in that the mixture is further stirred for at least 3 minutes after the addition of the compound of the formula I and / or II. Process according to one of Claims 6 to 10, characterized in that the aqueous sodium hydroxide solution at a concentration of 42 to 55% by weight contains builder-type substances. Process according to one of Claims 9 to 11, characterized in that the builder-type substances are added after addition of the compound of the formula I and / or II to an aqueous solution of sodium hydroxide having a concentration of 42 to 55% by weight. 13. Use of a water-containing, fixed-strength, variable-strength cleanser that provides at a temperature of 20 ° C in a penetration test according to ISO 2137 a value of up to 25 mm, preferably 0.1 to 25 mm, obtainable by a mixing process. · a) an aqueous alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular sodium hydroxide, preferably 42 to 55% in an amount of 21 to 70, preferably 35 to 55, 55% by weight and to increase viscosity b) a compound of formula I Cat ₂ CH (R ¹⁾ OR ² (I) wherein R represents a hydrogen atom and a methyl group r.ebp 2 R is independently hydrogen, alkyl of 1 to 4 atoms Q ·, £ - Λ 7 carbon, CK ₂ CH (R) OR 4 or CH 2 _? CH (R) OCH ₂ CH (R) OR, Where R, R and R are hydrogen or methyl acoms And R and R are hydrogen or alkyl of 1 to 4 carbon atoms, and / or compounds of formula II H0CH _of CK (R ⁸⁾ ~ '¹H (II) 2 ox x ^x O wherein R is hydrogen or methyl and x is an integer of 0, 1 or 2, in a total amount of 0.5 to M, preferably 1 to 10% by weight based on the total weight of the detergent, followed by solid alkali metal hydroxide, preferably potassium or sodium hydroxide, and in particular potassium hydroxide in an amount of up to 35, preferably 2 to 25% by weight, for surface cleaning. Use of the composition according to claim 13 for industrial machine dishwashing and household machine dishwashing. flflflfl flflfl flflfl flflflfl flflflfl flfl flflfl flfl flfl flfl flfl - 21 Use of the composition according to claims 13 or 14, wherein the composition additionally comprises a builder-type substance in an amount of up to 50, preferably 15 to 40% by weight, based on the total weight of the composition. Use of a composition according to claims 13 to 15, wherein the builder is selected from the group consisting of pentane sodium triphosphate, sodium citrate, nitrilotriacetate, ethylenediaminetetraacetate, sodium carbonate, alkali metal metasilicate, and mixtures thereof. Use of a composition according to claims 13 to 16, wherein the compound of formula I is selected from the group of ethylene glycol, The 1,2-propylene glycol, butyl glycol, butyldiglycol and the compound of formula II are selected from the group of ethanolamine, diethanolamine and triethanolamine. Use of a composition according to claims 13 to 17, characterized in that 1,2-propylene glycol is used as the compound of formula I and diethanolamine as the compound of formula II.